Conventionally, there has been studied to formulate a softening agent to a detergent for the purpose of preventing the loss of softness to have a stiff feel of the washed fibrous manufactured article due to the detachment of a fiber treating agent, deposition of salts or the like. For example, as a softening agent for giving softness to the feel of the fibrous manufactured article by the deposition of the softening agent on the fiber surface, a clay mineral such as smectite (see, for example, Patent Publication 1); a cationic surfactant such as a dialkylated quaternary ammonium salt (see, for example, Non-Patent Publication 1); a silicone such as poly(dimethyl siloxane) (see, for example, Patent Publication 2); and the like have conventionally been known to be formulated. Also, in recent years, studies have been made on a method of enhancing softening effects of a clay mineral from the viewpoint of easiness in formulation, environmental issue and the like. For example, there have been known a combined use of bentonite and a pentaerythritol compound (see, for example, Patent Publication 3), a combined use of a clay mineral and an aggregating agent (see, for example, Patent Publication 4), a combined use of bentonite and a soluble potassium salt (see, for example, Patent Publication 5 and Non-Patent Publication 1), and the like. In addition, there has been known that a so-called Ca-bentonite has a high softening ability, as compared to a Na-bentonite.
On the other hand, the trends of recent washing machine, such as lowered temperature of washing water and shortened operating time, in response to environmental and energy issues and economic advantages, all trigger a delay of a rate of dispersing clay granules such as smectite. Concerns that undispersed particles of clay mineral resulting from the delay remain on clothes have been increased.
Also, in recent years, as a part of reinforcement of detergency, especially a detergency against oil stains, a nonionic surfactant has been formulated as a main surfactant. However, as a result of intensive studies, the present inventors have found a disadvantage that if a nonionic surfactant is present in a detergent containing Ca-bentonite granules, dispersibility of clay granules is more likely to be remarkably lowered, and a combination of the formulation of nonionic surfactant and the Ca-bentonite causes the clay granules to remain on clothes, as with the trends of recent washing machine.    Patent Publication 1: JP-A-Showa-49-85102    Patent Publication 2: JP-A-2002-249799    Patent Publication 3: JP-A-Hei-5-140869    Patent Publication 4: JP-A-2002-541342    Patent Publication 5: JP-A-Hei-8-506843    Non-Patent Publication 1: Shuchi Kanyo Gijutsu Shu (Laundry Powder Detergent), published on Mar. 26, 1998